Wireless communication systems facilitate high-speed connectivity and data and voice transport from point-to-point and point-to-multipoint bases. Exemplary wireless communication systems include “Bluetooth™ protocol” enabled systems that facilitate the transport of data between Bluetooth enabled devices such as wireless headsets, cellular phones, laptop computers and personal digital assistants (PDAs), and “IEEE 802 protocol” systems that facilitate the transport of data over wireless local area networks (WLANs), which include devices such as desktop and laptop computers.
As is well known, Bluetooth is a global specification standard for radio communications operating in the unlicensed Industrial, Scientific, and Medical (ISM) band at 2.4 GHz. Bluetooth enabled devices, which are devices that comply with the Bluetooth Specification, replace normal cable connections with short-range radio links. Bluetooth offers a robust, low-complexity, low cost and low power cable-less connection solution. Bluetooth technology is featured in cordless telephony, intercom, facsimile (FAX) and Local Area Network (LAN) access, and dial-up networking applications. Bluetooth wireless communication protocols are implemented in wireless headsets, cellular phones, PDAs, printers, and other mobile devices. Bluetooth technology is described in more detail in a specification published by the Bluetooth Special Interest Group (SIG), entitled “Specification of the Bluetooth System, Version 1.2”, electronically available to the public via the well-known Internet at <http://www.Bluetooth.org>, published on Nov. 5, 2003, referred to herein as the “Bluetooth Specification,” and is hereby incorporated herein by reference in its entirety for its teachings on Bluetooth flow control, signals, devices and communication protocols and schemes.
In some applications, there is a need to send data intermittently and to do so with very low power consumption and at very low cost. Some examples of these applications are window sensors for security systems, light switches, TV/stereo remote control units, some location services, temperature sensors, and tire pressure gauges. In many cases, these same applications are being considered for use in the well-known “Zigbee” communication system.
Zigbee provides a relatively low power, low cost cable-less connection solution. In addition, many devices can be simultaneously inter-connected using the Zigbee approach. It has been argued by those supporting the Zigbee approach that Bluetooth wireless technology costs too much money, uses too much power, and cannot support more than seven devices without using a “park” state.
One concern associated with cost and power consumption in Bluetooth devices is necessitated by the software and its associated Random Access Memory (RAM) and Read Only Memory (ROM) (or Flash) requirements. The Bluetooth baseband is relatively simple. However, the software/firmware layers, and the variety of options and protocols lead to a significant percentage of chip die area. In a Host Controller Interface (HCI) solution, including the Radio Frequency (RF), Baseband, Link Manager Protocol, and Host Controller Interface layers (Parts A, B, C and E of Volume 2 of the Bluetooth Specification), the vast majority of code space is dedicated to the Link Manager Protocol (LMP) and HCI, and even the simplest task of establishing an Asynchronous Connectionless (ACL) data connection requires significant code.
One approach to providing a reduced complexity/cost/power short range wireless solution is to eliminate die area, and therefore cost as well as leakage current, by eliminating not only HCI, but also LMP and most of the baseband functions as well. A device that only supports the most basic baseband operations will be significantly more efficient than one that is able to establish basic ACL connections.
In June 2003, Ericsson announced a simplified version of Bluetooth Wireless Technology referred to by the press as “Bluetooth Lite.” At the time of Ericsson's announcement, a simplified version of Bluetooth, according to Ericsson, was “in an investigative stage” and no details of the Media Access Controller (MAC) were provided. The article and a presentation given at the Bluetooth World Congress in June 2003 proposed that the Bluetooth Physical Layer (PHY) would be used in “Bluetooth Lite” and that the existing Bluetooth MAC would be substantially reduced. A need therefore exists for a reduced-complexity MAC that could be adapted for use with the “Bluetooth Lite” concept suggested by Ericsson. It is also advantageous to provide a reduced-complexity solution that can be adapted for use as an independent feature in a future release of the incorporated Bluetooth Specification.
Therefore, a need exists for a method and apparatus that offers a very low complexity, low cost, and low power version of Bluetooth Wireless Technology that can accommodate devices targeted towards this market segment.